[flake8-comprehensions] C413 autofix bug

[zariiii9003]

The autofix for C413 can lead to bugs if the key parameter is used. Here is a little code example to show, that the results before and after the autofix are different.

original = [(1, 0), (2, 0), (3, 1), (4, 1)]
print(list(reversed(sorted(original, key=lambda x: x[1]))))
print(sorted(original, key=lambda x: x[1], reverse=True))

Here is the output:

[(4, 1), (3, 1), (2, 0), (1, 0)]
[(3, 1), (4, 1), (1, 0), (2, 0)]

[charliermarsh]

Do reversed(...) and reverse=True break ties differently?

[charliermarsh]

Yeah, it looks like reversed does a full reversal, whereas reverse ends up retaining the original order for ties.

[dhruvmanila]

Wow, didn't know about this. I think the solution would be to make the auto-fix "sometimes" and not fix it when there's a key parameter present. The key parameter makes the sorting different for reversed and sorted(..., reverse=True).

Edit: Not making the auto-fix "sometimes" but rather not flagging this.